Actually a lot of vendors care. In the past I’ve built Resume search engines using HRXML components. There are parsers, classifiers, viewers, search engines, and many other tools available for HRXML.

It’s a fairly well thought out spec in my opinion. Most issues I’ve run into have been from individuals that hate any use of XML and hastily convert the data to an ad hoc JSON format without thinking about why the XML is formatted the way it is. I presume this issue is why they created HR-JSON as a companion for uses where JSON is preferable.